SAN FRANCISCO
— JANE DOE can buy a ``hit'' of crack cocaine for $10. If she uses it while she is pregnant, society could pay up to $100,000 to care for her child during the first three months of its life. Staggering numbers of drug-addicted infants - born in tandem with the rise of cheap, accessible crack cocaine - are causing a crisis in hospital nurseries across the country. But even as physicians strive to help these babies, they warn that America's struggle to care for these children is only beginning.

Already, health-care services are showing signs of strain. Late last month, a private medical clinic in Oakland, Calif., closed its doors, citing high costs associated with treating ``crack babies'' and other cocaine-related health problems. Maxicare's closure left county officials scrambling to find alternative care for 8,000 patients - in a public-health system that is already overloaded.

But today's crisis in the maternity wards is likely to spread elsewhere as the children grow, experts warn. ``The biggest problems are down the line,'' says Judy Howard, who is conducting research on substance-addicted children for the National Institute on Drug Abuse. ``Wait until [these kids] hit school.''

The impact of the problem will be felt in foster care, day care, public schools, and other social services, specialists in the field say. ``Because of the nature of this drug, I feel we're about to see this whole situation blow up in our faces,'' says Cecele Quaintance, director of a perinatal outreach program operated by Stanford University Medical Center.

Physicians say cocaine is an especially pernicious drug, likely to cause more harm to an unborn child than most other illicit substances are. A woman who uses cocaine even once during her pregnancy, they say, can cause severe damage to the fetus, including stillbirth, spontaneous abortion, premature birth, and a wide array of problems associated with physical and neurological underdevelopment.

At least 1 in 10 new mothers has used illegal drugs during pregnancy, according to a survey conducted last year by the National Association for Perinatal Addiction Research and Education (NAPARE). As a result, 375,000 infants are annually exposed to potentially health-threatening drugs, according to the survey.

NAPARE president Ira J. Chasnoff cautions that these figures could be even higher. His survey of 36 hospitals nationwide showed that not all hospitals screen pregnant patients for drug use or test babies for the presence of drugs. ``Hospitals and private physicians think they are doing adequate screening, but they aren't,'' says Dr. Chasnoff, who is also director of the Perinatal Center for Chemical Dependence at Chicago's Northwestern Memorial Hospital.

In addition, the survey indicated that drug use during pregnancy is just as pervasive in the suburbs as it is in the cities, and among middle-class women as among poor women. But women who can afford private health care are harder to identify as drug users, because their doctors and hospitals are less likely to be looking for telltale signals of drug use.

The popularity of cocaine and its potent derivative, crack, reaches across all socioeconomic lines, experts say. Although physicians have long been concerned about the use of other drugs by pregnant women - including alcohol, nicotine, heroin, and methadone - the rising use of cocaine has created a problem of epidemic proportions, they say.

Los Angeles County, for example, has seen a 1,000 percent increase over the past four years in the number of drug-addicted infants - primarily attributable to crack, says Ms. Howard, an associate professor of pediatrics at the University of California at Los Angeles. But she suspects many other cases go undiagnosed. ``It's ridiculous to talk about these figures,'' she says. ``It scares me, we're missing so many cases.''

Although the medical community is learning how to identify drug-using women and their babies, experts are concerned that there will not be enough resources to help them. They cite, among other things, a need for more postnatal outreach programs and more drug-treatment programs for future mothers.

``If a poor woman came in tomorrow and wanted to get clean, we'd likely have no place to send her,'' Dr. Quaintance says.

But the key to halting the epidemic of crack babies is to get women off drugs. Indeed, Chasnoff's main focus is to work closely with new mothers so they can keep their babies rather than losing them to foster care.

But for children whose lives are already drug-affected, the future is uncertain. Experts say the children are likely to need costly services - from postnatal intensive care at a hospital to special-education programs in school. While much more research on the problem needs to be done, one thing is clear: The existing medical and social-service system is likely to be overwhelmed by the surging numbers of crack babies. ``With multi-thousands [of dollars] for each infant, crack babies are not profitable,'' says Richard Fulroth, a neonatalogist at Oakland's Children's Hospital.

Because most of these children are still so young, no one can predict what their needs will be years from now.

``As yet it's too early to tell,'' says Phil Callison, assistant superintendent for education in the Los Angeles Unified School District. In a pilot education program there to try to assess the needs of youngsters who were born drug-addicted, educators note that the children have problems adapting to change, retaining information, mastering language skills, and interacting with other children.